i dont know what is going on???

[Rus_lude00]

my buddy has a 97 and has had a rattling noise coming from the exhaust we jacked it up today and figured out when we will turn the tire one way it pulls the whole exahust forward and if we spin it the other way it would push the exhaust out we have no clue what is going on but ya if anyone has any ideas let me know... thanks

[THE ONE]

what do you mean when turn the tires one way the exhaust moves? they are not connected. at least they shouldn't be. as for the rattle from the exhaust that more than likely coming from the heat shield.

[Si Speed]

as for the rattle from the exhaust that more than likely coming from the heat shield.

X2. I have thissame problem but I'm just too lazy to get under there and fix it.

[Drew]

X3.. i have the same problem.. i just bent the heat shield a bit so it doesnt do it nearly as often.

[Rus_lude00]

we took the heat shield off the rattle is coming from inside the cat... but ya when it was on the jack stands we moved the tire and it caused the whole exhaust system to move it was weird... but if you stood behinde it you could see the muffler shaking... could it be a loose motor mount?

[1BadBB6]

make sure you check everything around the cat as far as the rattling goes, b/c a friend had an awful rattling coming from the exhaust and it ended up being something from the cat, but as far as the exhaust movin i have no idea that is some crazy stuff

[vervuurt]

Same happend to me. I thought it was the heat shield but it wasn't.
Check your Cat. I had mine removed and replaced with a straight pipe.
You are going to hear the vtec activate much harder because you just created a FREE-FLOW.
remember if you are going to do a straight pipe to custom make a connection so the AIR sensor can be connected again. Or your check engine light will go on.

[irk]

my exhaust likes to rattle at 2600 2700 with light gas or deceleration. Is this my heat shield?

[THE ONE]

yeah.... if not the heat shield could be some build up in the cat. Both have happened to me before.

[rheakpl]

yeup same thing...but its because i had a hi flow magnaflow..
let my friend drive my car in nyc and yeup big crater in the road = smashed my cat and stock header...

the honeycomb inside the cat OFTEN breaks and thus rattling....
just find out where the noise is coming from...knock on cat and try to reproduce sound...if its there then its there...straight pipe it or get a new cat..

heatshield would be next...make sure nothing is touching when car is moderately to heavily pushed..next would be anything else that might be rubbin..

dont know about how your whole exhaust sys moves at a turn of a wheel.....

[irk]

thanks guys, i didn't think to try knocking on it?

[BadMofo]

The exhaust moving with the wheel sounds very strange to me.

On a separate note, about you guys with noises coming from the catalytic converter... I agree with rheakpl. It is almost 100% definitely the honeycomb inside the cat. I was an assembler and welder for a HUGE catalytic converter manufacturer (probably shouldn't disclose the name, I have a non-compete contract with that that is still in place, and these are probably trade secrets :-P) for about 2 years of my life. We turned these ****in things out by the 10's of thousands a day. Now THAT is a racket, it costs the manufacturer damn near nothing to make them, the honeycomb and the "substrate" are the most expensive parts. There are all different shapes, hole patterns, sizes, and flow types for the honeycombs... but the most common ones cost about 20 dollars for a roughly 6 inch long block, and come 16 of these long blocks to a case. They then cut each block into 3 usable roughly 2" blocks, and only use 2 of these smaller blocks per catalytic converter.

So you're looking at 320 dollars for a box of the honeycomb material (16x$20). And out of that honeycomb material, you end up with 48 usable pieces of honeycomb. So for 320 dollars, you have enough blocks to make 24 catalytic converters... that's roughly 13 dollars per catalytic converter. Then you turn around and sell these catalytic converters for anywhere from 60-80 dollars for a universal cat, to 150-300 dollars for a direct fit cat (depending on how much piping is also involved). The pipe and metal is bought in bulk so its cheap as dirt. So all in all, not including what you pay your workers for labor, it costs a BIG catalytic converter manufacturer, less than 20 dollars to make something that they turn around and make anywhere from 200% to 1500% or more profit. And remember, we produced THOUSANDS of these a day. We supplied car manufacturing plants (most of the big American ones), exhaust shops, even aftermarket exhaust companies that include cats with their exhaust systems... We even were the sole manufacturer for Mac Motors (the company that makes the U.S. Post Office trucks) catalytic converters, and we made exhaust manifolds for them too.

They used to employ about 60 or 70 people doing various things in the shop... for every catalytic converter sold (not produced, but sold) they would take ONE PENNY and split it between all the workers there, and then at the end of the month, cut you a bonus based on that ammount. On a good month, we would EACH get 500 dollar or MORE bonuses.

Anyway, back to the reason your cat is probably the reason for the rattling...

The honeycomb is made out of mostly ceramic, and believe it or not, traces of platinum, and is VERY VERY easy to break. The "substrate" is like a flexible styrofoam type texture of material called something like vermiculite I believe. It's a kind of formica. Anyway, the cats come in two halves, and you wrap the honeycombs (there's usually 2 honeycombs per cat) in a piece of the substrate, place it in one half of the can, and then place the other half on top of it and tack weld it shut. You then seal it with a resistance seam welder, plasma cut a hole for the O2 sensor ring (if it's required for the cat), and weld pipe nipples into the ends and (if it's a direct fit cat) flanges on the ends of the pipe nipples. Once it's hooked up in place, and you fire the engine up for the first time, the heat from the exhaust solidifies the subtrate wrapped around the honeycomb and it locks it permanently in place, and also creates a cushion between the delicate honeycomb and the metal can. This cushion is roughly 1/4" thick at MOST at any given point, and when you seal the can around it, it compresses it even more, so you got maybe 1/16" to 1/8" of protection for a mostly hollow ceramic block inside of a metal can that is maybe 1/16" of an inch thick, riding under your multi thousand pound vehicle. In other words, if you hit the right object hard enough, on the right area of the cat... you're most definitely gonna hear some rattling... especially if only one of the honeycombs breaks, leaving debris in there that is blocked by the second honeycomb from blowing out the back of your exhaust. Hope that rambling tirade explains your rattling problem. You should probably replace your cat if that's the case... but think about it, if you broke your block good enough, you might actually see HP increases since there's less for your exhaust to travel through, kind of like a ghetto, noisy test pipe :tongue: . I'm not sure if the back pressure would be enough to get those pieces of honeycomb back up into your engine tho... cuz THAT would suck my friends.

[scmicromike]

I had the rattleing sound for the longest time. I hollowed out the cat in order to stop it. Worked fine that way for a while. now I am pulling a O2 sensor code (P0137) I wonder if the O2 sensor is bad or if hollowing the cat made for it to be too free flowing and it tripping the sensor. What do you guys think?

[sh98prelude]

I had the rattleing sound for the longest time. I hollowed out the cat in order to stop it. Worked fine that way for a while. now I am pulling a O2 sensor code (P0137) I wonder if the O2 sensor is bad or if hollowing the cat made for it to be too free flowing and it tripping the sensor. What do you guys think?


could be the O2 itself mine crapped out on me the other day and i pulled the same code at autozone the rep told me it was probably my test pipe but to try the sensor 1st so just bought a sensor again and installed good to go.

[scmicromike]

That is what I thought. how much did that run you?

[sh98prelude]

That is what I thought. how much did that run you?

80$ for both. installed at my dealership for free = good deall! lol got the denso "234-4621" part # i think same part number for sh or base its direct plug and play. like oem just unscrew and torque the new one in

[Brusly BB4]

****, I guess every Lude has that annoying rattle. It makes a ****ed up noise at low rpms. I'm glad to know that will disappear when I change the exhaust.